U.S. patent application number 17/464248 was filed with the patent office on 2021-12-23 for contact pad features.
The applicant listed for this patent is Magnecomp Corporation. Invention is credited to Kuen Chee Ee, David Glaess, Peter Hahn, Keith A. Vanderlee.
Application Number | 20210399653 17/464248 |
Document ID | / |
Family ID | 1000005814976 |
Filed Date | 2021-12-23 |
United States Patent
Application |
20210399653 |
Kind Code |
A1 |
Ee; Kuen Chee ; et
al. |
December 23, 2021 |
Contact Pad Features
Abstract
An electrical connection structure for connecting a
piezoelectric element and an electrical circuit to each other with
a conductive adhesive is described. The electrical connection
structure includes an epoxy, a conductive component surrounded by
the epoxy, and a trace feature implemented on top of the electrical
connection structure.
Inventors: |
Ee; Kuen Chee; (Chino,
CA) ; Hahn; Peter; (Bangkok, TH) ; Glaess;
David; (Bangkok, TH) ; Vanderlee; Keith A.;
(Midland, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Magnecomp Corporation |
Murrieta |
CA |
US |
|
|
Family ID: |
1000005814976 |
Appl. No.: |
17/464248 |
Filed: |
September 1, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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16701059 |
Dec 2, 2019 |
11121647 |
|
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17464248 |
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62779378 |
Dec 13, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 41/0475 20130101;
H02N 2/065 20130101; H02N 2/0085 20130101; H02N 2/028 20130101;
G11B 5/483 20150901 |
International
Class: |
H02N 2/00 20060101
H02N002/00; H01L 41/047 20060101 H01L041/047; G11B 5/48 20060101
G11B005/48; H02N 2/06 20060101 H02N002/06; H02N 2/02 20060101
H02N002/02 |
Claims
1-4. (canceled)
5. An electrical connection structure for connecting a
piezoelectric element and an electrical circuit to each other with
a conductive adhesive, the electrical connection structure
comprising: an epoxy; at least one conductive component surrounded
by the epoxy; and at least one depression feature implemented on
top of the electrical connection structure, the at least one
depression feature is in electrical contact with the at least one
conductive component and configured to reduce thermal expansion,
and the at least one depression feature is configured to constrain
the epoxy and the at least one conductive component.
6. The electrical connection structure of claim 5, wherein the at
least one depression feature includes a circular depression
feature.
7. The electrical connection structure of claim 5, wherein the at
least one depression feature includes more than one torus
depression features.
8. The electrical connection structure of claim 5, wherein the at
least one depression feature includes more than two elongated
depression features arranged alongside one another.
9. The electrical connection structure of claim 5, wherein the at
least one depression feature includes more than two elongated
depression features arranged in a grid layout.
10-18. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 62/779,378 filed on Dec. 13, 2018, which is hereby
incorporated by reference in its entirety.
FIELD
[0002] Embodiments of the disclosure relate to the field of
suspensions for disk drives. More particularly, this disclosure
relates to the field of multi-layer bond pads for a suspension.
BACKGROUND
[0003] A typical disk drive unit includes a spinning magnetic disk
containing a pattern of magnetic storage medium ones and zeroes.
The pattern of magnetic storage medium ones and zeroes constitutes
the data stored on the disk drive. The magnetic disk is driven by a
drive motor. The disk drive unit also includes a disk drive
suspension to which a magnetic read/write head is mounted proximate
a distal end of load beam. The "proximal" end of a suspension or
load beam is the end that is supported, i.e., the end nearest to
the base plate which is swaged or otherwise mounted to an actuator
arm. The "distal" end of a suspension or load beam is the end that
is opposite the proximal end, i.e., the "distal" end is the
cantilevered end.
[0004] The suspension is coupled to an actuator arm, which in turn
is coupled to a voice coil motor that moves the suspension
arcuately in order to position the head slider over the correct
data track on the data disk. The head slider is carried on a gimbal
which allows the slider to pitch and roll so that it follows the
proper data track on the disk, allowing for such variations as
vibrations of the disk, inertial events such as bumping, and
irregularities in the disk's surface.
[0005] Both single stage actuated disk drive suspensions and dual
stage actuated (DSA) suspension are known. In a single stage
actuated suspension, only the voice coil motor moves the
suspension.
[0006] Suspensions for hard disk drives and other devices such as
optical disk drives include a multi-layer circuit that carries
signals between the read/write head, and possibly other parts of
the suspension. For example, the signals can be carried between one
or more microactuators located on the suspension, to the rest of
the circuitry within the disk drive. Currently, it is common for
suspension circuits to employ vias to form electrical connections
between different layers. Vias may be used to connect trace layers
such as in interleaved traces for low impedance/high bandwidth
interconnects, to connect signal traces to bond pads, to connect a
signal trace to a grounded portion of the stainless steel
suspension, and to connect other circuit components.
SUMMARY
[0007] An electrical connection structure for connecting a
piezoelectric element and a wiring member to each other with a
conductive adhesive is described. The electrical connection
structure includes an epoxy, a conductive component surrounded by
the epoxy, and a copper trace feature implemented on top of the
electrical connection structure. In an alternative embodiment, the
electrical connection structure can include an epoxy, a conductive
component surrounded by the epoxy, and a depression feature
implemented on top of the electrical connection structure. The
copper trace feature is in electrical contact with the conductive
component to reduce thermal expansion. The copper trace feature
also provides constraints to the epoxy and the conductive
component.
[0008] In some embodiments, the copper trace feature includes a
circular copper trace feature. The conductive component can include
a vertical conductive component positioned in the center of the
circular copper trace feature. In an alternative embodiment, the
copper trace feature can include two elongated copper trace
features arranged alongside one another. The conductive component
can include a vertical conductive component positioned between the
two elongated copper trace features and a horizontal conductive
component abutting the two elongated copper trace features.
[0009] In some embodiments, the depression feature includes a
circular depression feature. In an alternative embodiment, the
depression feature can include multiple torus depression features.
Furthermore, the depression feature can include multiple elongated
depression features arranged alongside one another. Moreover, the
depression feature can include multiple elongated depression
features arranged in a grid layout.
[0010] A dual stage actuated assembly is also provided. The dual
stage actuated assembly includes a piezoelectric microactuator
mounted near a first end of the dual stage actuated assembly and a
flexure mounted near a second end of the dual stage actuated
assembly. The flexure includes an electrical circuit which includes
a copper contact pad configured to carry a driving voltage to the
at least one piezoelectric microactuator. The copper contact pad
includes an epoxy, a conductive component surrounded by the epoxy,
and a copper trace feature implemented on top of the electrical
connection structure. In an alternative embodiment, the copper
contact pad can include an epoxy, a conductive component surrounded
by the epoxy, and a depression feature implemented on top of the
electrical connection structure, wherein the at least one copper
trace feature is in electrical contact with the at least one
conductive component to reduce thermal expansion.
[0011] The above summary is not intended to represent each
embodiment or every aspect of the present disclosure. Rather, the
foregoing summary merely provides an example of some of the novel
aspects and features set forth herein. The above features and
advantages, and other features and advantages of the present
disclosure, will be readily apparent from the following detailed
description of representative embodiments and modes for carrying
out the present invention, when taken in connection with the
accompanying drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] In order to describe the manner in which the advantages and
features of the disclosure can be obtained, embodiments of the
present disclosure are described with reference to specific
examples illustrated in the appended drawings. These drawings
depict only example aspects of embodiments of the present
disclosure, and are therefore not to be considered as limiting of
its scope. The principles are described and explained with
additional specificity and detail through the use of the following
drawings.
[0013] FIG. 1 illustrates a DSA suspension and a contact pad;
[0014] FIG. 2A illustrates the contact pad in further detail;
[0015] FIG. 2B illustrates thermal expansion of an epoxy on the
contact pad in further detail;
[0016] FIG. 3 illustrates a contact pad, in accordance with an
embodiment of the disclosure;
[0017] FIG. 4 illustrates a circular trace feature on top of a
contact pad, in accordance with an embodiment of the
disclosure;
[0018] FIG. 5 illustrates a grid of trace features within a contact
pad, in accordance with an embodiment of the disclosure;
[0019] FIG. 6 illustrates a circular depression feature within a
contact pad, in accordance with an embodiment of the
disclosure;
[0020] FIG. 7 illustrates a torus depression feature within a
contact pad, in accordance with an embodiment of the
disclosure;
[0021] FIG. 8 illustrates elongated depression features within a
contact pad, in accordance with an embodiment of the disclosure;
and
[0022] FIG. 9 illustrates multiple depression features within a
contact pad, in accordance with an embodiment of the
disclosure.
DETAILED DESCRIPTION
[0023] The embodiments of the present disclosure are described with
reference to the attached figures, wherein like reference numerals
are used throughout the figures to designate similar or equivalent
elements. The figures are not drawn to scale, and they are provided
as exemplary illustrations. Several aspects of the embodiments are
described below with reference to example applications, which are
not intended to limit the scope of this disclosure. It should be
understood that numerous specific details, relationships, and
methods are set forth to provide a full understanding of the
embodiments.
[0024] One having ordinary skill in the relevant art, however, will
readily recognize that the invention can be practiced without one
or more of the specific details, or with other methods. In other
instances, well-known structures or operations are not shown in
detail to avoid obscuring the embodiments. Embodiments of the
present disclosure are not limited by the illustrated ordering of
acts or events, as some acts may occur in different orders and/or
concurrently with other acts or events. Furthermore, not all
illustrated acts or events are required to implement a methodology
in accordance with the present invention.
[0025] FIG. 1 illustrates a DSA suspension 10. The DSA suspension
10 includes two piezoelectric microactuators (PZTs) 14 mounted near
a gimbal. The gimbal allows the slider to pitch and roll so that it
follows the proper data track on the disk, allowing for such
variations as vibrations of the disk, inertial events such as
bumping, and irregularities in the disk's surface. The PZTs 14 act
directly on the gimbal through flexible connectors. Such
suspensions are sometimes called gimbal DSA suspensions, or simply
GSA suspensions. A GSA suspension is one type of DSA suspension.
Other arrangements of PZTs can be used to actuate suspensions,
including, but not limited to, tri-stage actuated suspensions. In
FIG. 1, the suspension 10 includes a flexure 20, which is mounted
to a load beam 12. The flexure 20 includes an electrical circuit
22, which includes copper contact pads 24 configured to carry the
PZT driving voltage. The electrical circuit 22 also includes copper
contact pads 28, which are grounded. In some embodiments, an
electrically conductive adhesive (ECA) is used to create an
electrical bridge connecting the copper contact pad 24 to a top
electrode of the PZTs 14.
[0026] During the assembly process, the ECA is cured at a high
temperature. After the curing process, the epoxy component of the
ECA will often shrink. This shrinkage ensures that the silver
particle component of the ECA will be connected to the bonding
surface for electrical connection. After the curing process, the
DSA suspension 10 undergoes a series of tests to ensure maximum
performance. One of these tests include an in-situ test, in which
the DSA suspension 10 undergoes a high temperature cycle for up to
100 hours. During the in-situ test, the capacitance and resistance
are monitored to ensure that good electrical connection is
maintained during the test. Thus, it is imperative to maintain a
stable electrical connection for the PZT 14. Joint 26, located
between the ECA and the copper contact pad 24, is typically prone
to in-situ failure.
[0027] FIGS. 2A and 2B illustrate the copper contact pad 24 in
further detail. The copper contact pad 24 can include an epoxy 27
and an exemplary silver component 28. The exemplary silver
component 28 is simplified for the current disclosure to illustrate
the contact with the copper contact pad 24. As shown in FIG. 2A,
the exemplary silver component 28 is surrounded by the epoxy 27.
The high temperature during the in-situ test causes thermal
expansion of the epoxy 27 of the ECA. This thermal expansion tends
to pull the exemplary silver component 28 from the copper contact
pad 24. This separation between the exemplary silver component 28
and the copper contact pad 24 causes an electrical disconnection
when the pulling force is large enough at high temperature.
[0028] FIG. 2B illustrates the thermal expansion of the epoxy 27.
The exemplary silver component 28 is pulled away from the copper
contact pad 24. In some embodiments, the average contact pressure
between the exemplary silver component 28 and the copper contact
pad 24 is -4.55 MPa. To alleviate the electrical disconnection, the
present disclosure provides various connections between an
exemplary conductive component and a contact pad that withstand
thermal expansion.
[0029] FIG. 3 illustrates a contact pad 34 in accordance with an
embodiment of the disclosure. The contact pad 34 can include an
epoxy 37 and exemplary conductive components 38 and 39. For some
embodiments, the contact pad 34 is formed as a copper contact pad.
However, other conductive materials could be used. For some
embodiments, the conductive components 38 and 39 are formed of
silver. However, other conductive materials could be used to form
the conductive components described herein. The contact pad 34 can
also include additional trace features 40 that create a rough
surface for the copper contact pad 34. The exemplary conductive
components 38 and 39 are illustrated in a simplified format in the
current disclosure to illustrate the contact with the copper
contact pad 34. The exemplary conductive components 38 and 39 are
surrounded by the epoxy 37.
[0030] The additional copper trace features 40 can be implemented
on top of the contact pad 34 to promote electrical contact with the
side walls of the copper trace features 40 and the exemplary
conductive components 38 and 39. This additional side wall
electrical contact reduces the thermal expansion effect during high
temperature cycle. The additional trace features 40 can also
provide more constraints to the epoxy 37 and the exemplary
conductive components 38 and 39. According to some embodiments, the
trace features are formed of copper. However, other conductive
materials could be used. This constraint reduces the pulling force
away from the contact pad 34 at high temperatures.
[0031] Furthermore, the contact between the additional trace
features 40 and the silver 38 provides a shearing tendency, which
maintains electrical contact when the thermal force is causing the
conductive components 38 and 39 to pull away from the contact pad
34.
[0032] Table 1 illustrates the effect of having the additional
trace features 40 on the contact pressure between the exemplary
conductive components 38 and 39 and the contact pad 34 according to
some embodiment. The negative pressure represents the tendency of
pulling away from the contact pad 34 at high temperature during an
in-situ test. The horizontal conductive component 38 connection to
the sidewall is most effective when the additional trace features
40 are thicker.
TABLE-US-00001 TABLE 1 Modelling Results Contact Pressure (MPa) Cu
trace height 10 um 5 um 2 um Vertical silver connection -2.85 -3.92
-4.22 Horizontal silver connection -0.6 -1.4 -4.36
[0033] It should be understood that other configurations of the
additional trace features 40 can be implemented to achieve similar
results. For example, FIG. 4 illustrates a circular trace feature
41 on top of the copper contact pad 34. According to some
embodiments, the trace features are formed of copper. However,
other conductive materials could be used. The circular trace
feature 41 can surround a vertical conductive component 43. The
circular trace feature 41 can provide constraints to the epoxy 37
and the vertical conductive component 43. This constraint reduces
the pulling force of the vertical conductive component 43 away from
the contact pad 34 at high temperatures.
[0034] FIG. 5 illustrates a grid of trace features 42 within the
contact pad 34. Similar to the embodiment discussed in FIG. 3, the
grid of copper trace features 42 can be on the contact pad 34 to
promote electrical contact with the side walls of the trace
features 42 and the exemplary conductive components. Electrical
contact with side wall has shearing tendency during thermal
expansion, which maintains electrical contact as the thermal force
is to pull away from pad 34. This additional trace features 42
reduce the thermal expansion effect during high temperature. The
grid of trace features 42 can also provide more constraints to the
epoxy and the exemplary conductive components. This constraint
reduces the pulling force away from the contact pad 34 at high
temperatures.
[0035] Alternatively, instead of adding additional trace features
on top of the contact pad 34, a similar result can be achieved by
creating a depression or subtraction of the contact pad 34. FIGS.
6-9 provide exemplary illustrations of these alternative
embodiments.
[0036] FIG. 6 illustrates a circular depression feature 43 within
the copper contact pad 34. The circular depression feature 43 can
be implemented to promote electrical contact with the side walls of
the circular depression feature 43 and the exemplary conductive
components. This additional electrical contact reduces the thermal
expansion effect during high temperature. The circular depression
feature 43 can also provide more constraints to the epoxy and the
exemplary conductive components. This constraint reduces the
pulling force away from the contact pad 34 at high
temperatures.
[0037] FIG. 7 illustrates a torus depression feature 44 within the
copper contact pad 34. The torus depression feature 44 can be
implemented to promote electrical contact with the side walls of
the torus depression feature 44 and the exemplary conductive
components (also not shown). This depression feature 44 reduces the
thermal expansion effect during high temperature cycle. The torus
depression feature 44 can also provide more constraints to the
epoxy and the exemplary conductive components. This constraint
reduces the pulling force away from the contact pad 34 at high
temperatures.
[0038] FIG. 8 illustrates elongated depression features 45 within
the contact pad 34. The elongated depression features 45 can be
implemented to promote electrical contact with the side walls of
the elongated depression features 45 and the exemplary conductive
components. This elongated depression features 45 reduces the
thermal expansion effect during high temperature cycle. The
elongated depression features 45 can also provide more constraints
to the epoxy and the exemplary conductive components. This
constraint reduces the pulling force away from the contact pad 34
at high temperatures.
[0039] FIG. 9 illustrates multiple depression features 46 within
the copper contact pad 34. The multiple depression features 46 can
be implemented as a grid of elongated depressions to promote
electrical contact with the side walls of the multiple depression
features 46 and the exemplary conductive components. This multiple
depression features 46 reduce the thermal expansion effect during
high temperature cycle. The multiple depression features 46 can
also provide more constraints to the epoxy and the exemplary
conductive components. This constraint reduces the pulling force
away from the contact pad 34 at high temperatures.
[0040] It should be understood that other configurations and shapes
of depression features can be implemented herein.
[0041] The previous description of the disclosure is provided to
enable any person skilled in the art to make or use the disclosure.
Various modifications to the disclosure will be readily apparent to
those skilled in the art, and the generic principles defined herein
can be applied to other variations without departing from the scope
of the disclosure. Thus, the disclosure is not intended to be
limited to the examples and designs described herein, but is to be
accorded the widest scope consistent with the principles and novel
features disclosed herein.
* * * * *